misc - congenital, zoonotic, arbo viruses
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Congenital Viral Infections
Congenital, Perinatal, and Neonatal Viral Infections
Intrauterine• Rubella• CMV• HSV• VZV• HIV• HTLV-1• Hepatitis B • Hepatitis C• Parvovirus B19• Lassa Fever• Japanese Encephalitis
Perinatal and Neonatal• HSV• VZV• HIV• HTLV-1• Hepatitis B• Hepatitis C
Arthropod-borne Viruses (Arboviruses)
Are viruses that can be transmitted to man by arthropod vectors
Arthropod Vectors
MosquitoesDengue, yellow fever
TicksCrimean-Congo haemorrhagic fever
SandfliesRift valley fever
Examples of Arthropod Vectors
Phlebotmine SandflyCulex Mosquito
Assorted TicksAedes Aegypti
Dengue Fever
• The biggest arbovirus problem in the world today with over 2 million cases per year
• Dengue is found in SE Asia, Africa and S America.
• Transmitted by Aedes mosquitoes residing in water-filled containers.
• Transmission cycle: human-mosquitoe-human
Distribution of Dengue
• High fever, lymphadenopathy, myalgia, bone and joint pains, headache, and a maculopapular rash.
• Severe cases may present with haemorrhagic fever and shock with a mortality of 5-10%. (Dengue haemorrhagic fever or Dengue shock syndrome)
Dengue Fever
Dengue Haemorrhagic Fever
Dengue Fever
• Diagnosis : by serology.• Treatment: no specific antiviral therapy.• Prevention
Mosquito eradication. Removal of all containers from premises which
may serve as vessels for egg deposition. A live attenuated vaccine is being tried in
Thailand with encouraging results.
Viral Zoonosis
Rabies Virus
Structure of rabies virus
(CDC)
• Characteristic bullet-shaped appearance
• ssRNA enveloped virus
Epidemiology
• Rabies is a zoonosis which is prevalent in wildlife. • The animals involved differ from continent to continent.• Wide range of hosts: fox, bats wolf dog
Rabies: Pathogenesis
Rabid animals become aggressive
and harbor the virus in saliva
Rabies: Clinical Features
• Incubation Period depends on: Infective dose Site of animal bite
• Prodromal Period (up to two weeks) Pain or itching at the site of the wound, Fever & headache.
• CNS infection (Neurological phase) Hydrophobia in half of the patients. Seizures and hallucinations. Paralysis leading to respiratory failure Coma & death
Laboratory Diagnosis
Histopathology (Negri Bodies)• Are pathognomonic of rabies • Are intracytoplasmic inclusions
formed by aggregates of nucleocapsids in neurons of about 90% of infected humans
Negri Body in neuron cell (CDC)
Rapid virus antigen detection
Positive DFA test (CDC
Laboratory Diagnosis
Virus Cultivation
Serology
Management and PreventionPre-exposure Prophylaxis • Inactivated rabies vaccine to high risk persons like vets,
animal handlers, laboratory workers etc.
Post-exposure Prophylaxis • In cases of animal bites, dogs and cats in a rabies endemic
area should be held for 10 days for observation. If signs develop, they should be killed and their tissue examined.
• Local treatment of wounds• Passive immunization - human rabies immunoglobulin • Active immunization - the human diploid cell vaccine is
usually administered into the deltoid region, and 5 doses are usually given.
Established Rabies• Nothing much can be done except
intensive supportive care.
• To date, only 2 persons with proven rabies have survived.
Management and Prevention
Control of Rabies
• Urban - canine rabies: 99% of all human rabies. – Dog control– Vaccination of dogs – Quarantine of imported animals
• Wildlife - much more difficult to control.
• G Protein (Surface glycoprotein) – Binds to cellular receptors and is the target of
neutralizing antibodies• M (matrix) protein.
– This is a peripheral membrane protein may act as a bridge between the membrane or G protein and the nucleocapsid.
• N (Nucleoprotein) protein– This is the major structural protein that covers
the RNA genome and protects it from nucleases. • L (Large) protein
– Its gene takes up 60% of the genome• P (phospho)) protein
Rabies Virus Proteins